1. Field of Invention
This invention relates to compactable tubular assemblies, such as tent poles, specifically to a locking for holding an internal elastic cord in such poles.
2. Prior Art
Most contemporary tent poles are composed of several tubular sections which are joined with tubular inserts. An insert is affixed to one end of a section so that it extends beyond the end of the section to form a male end. The extending male end is arranged to slip int an open, female end of an adjacent section. All the pole's sections are connected by an internal elastic cord under tension, which draws the sections together, or allows them to be unjointed and folded. The elastic cord is usually held in position within the pole by way of knotted cord ends and washers seated behind the inserts of the end sections of the pole.
The elastic cord must be threaded through the entire length of the pole in order to make the cord accessible for installation of washers (which lock the cord's end sin the sections) and knotting. However, the elastic cord, when tensioned and held in position, extends only from the end section insert at one end of the pole, through the pole's inner sections, to the end section insert at the opposite end of the pole. It does not extend the entire length of the pole. The ends of the tent pole usually have end tips which fit into grommets in webbing tabs sewn to the tent, although some tent designs require that the ends of the tent pole be open, without end tips.
The above tent pole assembly technique produces a tent pole which functions well in use, but presents difficulties when the pole must be disassembled for repair due to damage, or when the pole's elastic cord becomes slack and must be tensioned again. The elastic cord must be cut, preferably next to the insert of one of the end sections of the tent pole. Next, the end tip, if it is of the pres-fit type, must be removed from this now loose end section so that the knotted cord end and washer can be removed from within this pole section. Removing a press-fit end tip from its pole section usually damages the tip so that it almost always must be replaced with a new tip. If the end tip is affixed to its section with glue or by staking, both the section and the tip must be replaced with a new section and tip. Next, the damaged sections of the tent pole must be replaced with new ones and the pole reassembled. Finally, the new end tip must be affixed to its end section. This same procedure must be followed if the tent pole's elastic cord needs additional tension. Some of these steps require special tools and experience to be done effectively, so tent pole repair or elastic cord tensioning usually can not be done by the tent owner, or even by average retail store personnel.
Elastic cord holding devices, such as wire spring devices, have been made and used in the past, but these devices will not be discussed because their main purpose was not to facilitate the manufacture, repair, or elastic cord tensioning, but rather just to hold the elastic cord in position.
One end tip has been developed specifically for tent poles. Its purpose and advantages over existing techniques are easier tent pole manufacture, repair, and elastic cord tensioning. This end tip was designed to hold the tensioned elastic cord in position at the ends of the pole, and the tension of the elastic cord was supposed to hold the end tip on to the pole ends. However any advantages which this end tip design might offer, in terms of convenience of manufacture, repair, or elastic cord tensioning, are far outweighed by its disadvantages, which are:
(a) The end tip can be pulled completely out of the end of the pole during the removal of the pole from the tent. This is because only the tension of the elastic cord is holding the end tip on to the pole end. End tips tend to bind in their mating grommet because of their angle of engagement. This binding force can exceed the pulling force of the elastic cord, causing the end tip to be pulled out of the pole end, causing the tip and the cord to separate. The entire pole will come apart as a result of this failure.
(b) Tent poles using this type of end tip are limited in their use because they cannot be used with tents which require poles with open ends.
(c) The elastic cord must extend the entire length of the tent pole, from end to end tip, unlike current assembly technology where the cord extends only through the inner sections of the pole. The additional cord adds weight and cost to the pole.